Handover apparatus and method for avoiding in-device coexistence interference

ABSTRACT

The present disclosure relates to a handover apparatus and method capable of avoiding in-device coexistence interference. In order to prevent handover failure due to in-device coexistence interference, an SeNB provides TDM information (including TDM pattern information or TDM activation information) to a UE during a handover procedure, and the UE performs the handover with a TeNB according to the provided TDM information. By the disclosure, the UE can perform ISM signal transmission/reception and LTE signal transmission/reception with the TeNB in a discriminated manner according to a particular TDM pattern, so as to prevent handover failure due to the in-UE coexistence interference.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage Entry of InternationalApplication PCT/KR2012/002292, filed on Mar. 28, 2012, and claimspriority from and the benefit of Korean Patent Application No.10-2011-0030411, filed on Apr. 1, 2011, both of which are incorporatedherein by reference in their entireties for all purposes as if fully setforth herein.

BACKGROUND

1. Field

The present invention relates to a wireless communication system, andmore particularly, to a handover apparatus and a handover method capableof avoiding in-device coexistence interference.

2. Discussion of the Background

With the development of communication systems, consumers includingcompanies and individuals require wireless communication terminalssupporting various services.

Current mobile communication systems, such as 3GPP (3rd GenerationPartnership Project), LTE (Long Term Evolution), and LTE-A (LTEAdvanced), are requiring development of technology for a high-speedlarge-capacity communication system, which can transmit or receivevarious data, such as images and wireless data, beyond the capability ofmainly providing a voice service, and can transmit data in a largecapacity such as that transmitted in a wired communication network.Moreover, the current mobile communication systems are inevitablyrequiring a proper error detection scheme, which can minimize thereduction of information loss and improve the system transmissionefficiency, thereby improving the system performance.

In this regard, a terminal apparatus, i.e. a User Equipment (UE)apparatus, or an evolved Node-B (eNB) apparatus is required to besimultaneously provided with various types of modules for supportingvarious types of wireless communication schemes or systems. Actually, aUE or eNB apparatus is simultaneously provided with various modules,which include not only long range wireless communication modules, suchas LTE (including LTE antenna, LTE RF device, and LTE baseband device),but also short range wireless communication modules, such as Bluetoothand Wi-Fi, and modules for receiving Global Positioning Service (GPS)signals.

Such a simultaneous use of various modules may cause data transmissionor reception in one particular module to act as an interference to datatransmission or reception in another module, which can be expressed asan “in-device coexistence interference”. The following discussionemploys a UE as an example of a communication device. Therefore, thein-device coexistence interference may be also expressed as “in-UEcoexistence interference”.

In order to avoid such in-UE coexistence interference, various schemesare being discussed. However, when a UE performs a handover from asource eNB to a target eNB, such in-UE coexistence interference maycause a handover failure or a Radio Link Failure (RLF). Therefore, therehave been requirements for solving this problem, but there have been nodiscussions thereon yet.

Therefore, the present disclosure is intended to present a handoverprocess capable of avoiding occurrence of an RLF or a handover failuredue to in-UE coexistence interference.

SUMMARY

An exemplary embodiment of the present invention is to provide ahandover apparatus and a handover method in a wireless communicationsystem.

Another exemplary embodiment of the present invention is to provide anapparatus and a method capable of avoiding in-device coexistenceinterference in a wireless communication system.

Another exemplary embodiment of the present invention is to provide ahandover apparatus and a handover method capable of avoiding in-devicecoexistence interference in a wireless communication system.

Another exemplary embodiment of the present invention is to provide atechnology for transmitting Time Division Multiplexing (TDM) activationinformation or TDM pattern information capable of avoiding in-devicecoexistence interference to a UE by an eNB at the time of handover.

Another exemplary embodiment of the present invention is to provide anapparatus and a method for performing a process of setting a RandomAccess Channel (RACH) including TDM pattern information.

Another exemplary embodiment of the present invention is to provide anapparatus and a method for transmitting a Radio Resource Control (RRC)connection reconfiguration message including TDM pattern information.

Another exemplary embodiment of the present invention is to provide anapparatus and a method for performing an RRC connection reconfigurationprocess including TDM pattern information.

Another exemplary embodiment of the present invention is to provide anapparatus and a method for transmitting and receiving data according toTDM pattern information.

An exemplary embodiment of the present invention provides a handovermethod of a UE for avoiding in-device coexistence interference, whichincludes: receiving an RRC connection reconfiguration message includingTDM information for avoiding in-UE coexistence interference from ahandover Source eNB (SeNB); and performing a handover operation based onthe TDM information with a target eNB (TeNB) based on the TDMinformation.

Another exemplary embodiment of the present invention provides ahandover method of an SeNB for avoiding in-UE coexistence interference,which includes: generating an RRC connection reconfiguration messageincluding TDM information for avoiding in-UE coexistence interference;and transmitting the RRC connection reconfiguration message includingthe TDM information to a UE to be handovered.

Another exemplary embodiment of the present invention provides ahandover method of a TeNB for avoiding in-UE coexistence interference,which includes: receiving a contention-free random access preamble froma UE to be handovered; and performing a handover procedure with the UEaccording to particular TDM information for avoiding in-UE coexistenceinterference.

Another exemplary embodiment of the present invention provides ahandover apparatus for avoiding in-UE coexistence interference, whichincludes: an RRC connection reconfiguration message receiver forreceiving an RRC connection reconfiguration message from an SeNB forhandover; a TDM determiner for determining whether the RRC connectionreconfiguration message includes TDM information for avoiding in-UEcoexistence interference; an RA execution unit for performing a randomaccess with the SeNB; and a transceiver for performing a handoverbetween the SeNB and a TeNB based on the TDM information.

Another exemplary embodiment of the present invention provides an SeNBapparatus for performing a handover for avoiding in-UE coexistenceinterference, which includes: an RRC connection reconfiguration messagegenerator for, when a TDM operation is necessary in order to avoid in-UEcoexistence interference, generating an RRC connection reconfigurationmessage including TDM pattern information or TDM activation information;and a message transmitter for transmitting the generated RRC connectionreconfiguration message to the UE.

Another exemplary embodiment of the present invention provides a TeNBapparatus for performing a handover for avoiding in-UE coexistenceinterference, which includes: an RA processor for receiving acontention-free random access preamble from a UE to be handovered; a TDMdeterminer for determining whether to perform a TDM operation betweenthe TeNB apparatus and a corresponding UE, an access grant processor forgenerating an access grant message according to predetermined TDMinformation and transmitting the generated access grant message to theUE, and a transceiver for receiving an RRC connection reconfigurationcomplete message from the UE according to a predetermined TDM pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 illustrates examples of RLF which may occur due to in-UEcoexistence interference;

FIG. 2 is a signal flow diagram of a handover method for avoiding in-UEcoexistence interference according to an embodiment of the presentinvention;

FIG. 3 illustrates a DRX-based TDM scheme, which is one of schemes foravoiding in-UE coexistence interference applicable to the presentembodiment;

FIG. 4 illustrates an HARQ protection TDM scheme, which is one ofschemes for avoiding in-UE coexistence interference applicable to thepresent embodiment;

FIG. 5 illustrates an autonomous denial TDM scheme, which is one ofschemes for avoiding in-UE coexistence interference applicable to thepresent embodiment;

FIG. 6 is a flowchart of an operation of a UE during a handoverprocedure according to an embodiment of the present invention;

FIG. 7 is a flowchart of an operation of the SeNB during a handoverprocedure according to an embodiment of the present invention;

FIG. 8 is a flowchart of an operation of a TeNB during a handoverprocedure according to an embodiment of the present invention;

FIG. 9 is a block diagram of a UE according to an embodiment of thepresent invention;

FIG. 10 is block diagram of an SeNB according to an embodiment of thepresent invention; and

FIG. 11 is block diagram of a TeNB according to an embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention will bedescribed with reference to the accompanying drawings. In the followingdescription, the same elements will be designated by the same referencenumerals although they are shown in different drawings. Further, in thefollowing description, detailed explanation of known related functionsand constitutions may be omitted so as to avoid unnecessarily obscuringthe subject manner of the present invention. (PCT)

A wireless communication system is a system for providing variouscommunication services, such as voice and packet data, and includes aUE, usually implying a terminal, and an eNB corresponding to atransmitter side or cell.

A terminal or UE used herein has a general concept including a userterminal in a wireless communication, and should be interpreted as aconcept including all of a Mobile Station (MS) in a Global System forMobile Communication (GSM), a User Terminal (UT), a Subscriber Station(SS), and a wireless device, as well as UE in Wide Code DivisionMultiple Access (WCDMA), Long-Term Evolution (LTE), and High SpeedPacket Access (HSPA).

In general, an eNB corresponds to a device, a function or a particulararea communicating with a UE, and may be referred to by another name,such as Node-B, evolved Node-B, sector, site, Base Transceiver System(BTS), Access Point (AP), relay node, or Remote Radio Head (RRH).

In other words, in the present specification, the eNB should beinterpreted as having a comprehensive meaning, which includes not onlythe eNB itself of the LTE, but also both an area covered by eachtransmission side or cell, such as Node B of the WCDMA or Base StationController (BSC) of the CDMA, and a device or hardware/software forcontrolling the area, and may be used as the same concept as a megacell, a macro cell, a micro cell, a pico cell, a femto cell, a relaynode, or an RRH.

In order to satisfy the user service requirements according to highspeed data support, a wireless communication system to which the presentinvention is applied supports a plurality of component Carriers (CCs).Further, the wireless communication system supports a CarrierAggregation (CA) function, which groups a plurality of CCs and uses themas one system band. That is, the CA refers to a scheme of collectivelyusing a plurality of frequency bands for transmission by onecommunication apparatus.

Here, in the case of using the CA as described above, a transmissionarea including a combination of a downlink CC and an uplink CC may bedefined as a cell. Further, among the cells as defined above, a cellproviding a service to the device is called a serving cell.

In the case of FDD, a cell may be configured by a combination of one ormore downlink CCs and one or more uplink CCs. Also, in the case of FDD,the cell may be configured by only one or more downlink CCs. In the caseof TDD, a cell may have a form in which one CC includes both uplinktransmission and downlink transmission.

In the present specification, the term eNB is used as a representativeof a transmitter side or cell. However, the present invention is notlimited to such use, and the eNB should be construed as a comprehensiveconcept implying all types of wireless communication apparatusestransmitting or receiving data to or from a terminal or UE as describedabove.

There is no limit in the multiple access schemes applicable to thewireless communication system.

That is, the wireless communication system may employ various multipleaccess schemes, such as a Code Division Multiple Access (CDMA) scheme, aTime Division Multiple Access (TDMA) scheme, a Frequency DivisionMultiple Access (FDMA) scheme, an Orthogonal Frequency Division MultipleAccess (OFDMA) scheme, an OFDM-FDMA scheme, an OFDM-TDMA scheme, and anOFDM-CDMA scheme.

Uplink transmission and downlink transmission may employ a Time DivisionDuplex (TDD) scheme of transmitting data in different times, a FrequencyDivision Duplex (FDD) scheme of transmitting data by using differentfrequencies, or a Hybrid Division Duplex (HDD) scheme corresponding to ahybrid scheme of the two schemes.

The embodiment of the present invention may be applied to resourceallocation in an asynchronous wireless communication evolved to the LongTerm Evolution (LTE) and the LTE-Advanced (LTE-A) from the GSM, theWCDMA, and HAPA and a synchronous wireless communication evolved to theCDMA, the CDMA-2000, and the Ultra Mobile Broadband (UMB). The presentinvention is not limited to a specific wireless communication field andshould be interpreted to include all technical fields to which thespirit of the present invention can be applied.

Meanwhile, as described above, each of recent UEs and eNBs is requiredto be simultaneously equipped with a plurality of modules for supportingvarious types of wireless communication schemes or systems, and anactual UE or eNB is simultaneously equipped with various modules, whichinclude not only long range wireless communication modules (includingantenna, LTE RF, and LTE baseband device), but also short range wirelesscommunication modules, such as Bluetooth and Wi-Fi, and other modules,such as a GPS receiving module.

That is to say, one UE or eNB simultaneously includes a GPS module,including a GPS antenna, a GPS RF device, and a GPS baseband device, anLTE module, including an LTE antenna, an LTE RF device, and an LTEbaseband device, and a BT/Wi-Fi module, including a BT/Wi-Fi antenna, aBT/Wi-Fi RF device, and a BT/Wi-Fi baseband device. However, since theisolation between the antennas of such different modules is not perfect,interference between different types of wireless systems may occur andis called “in-device coexistence interference”.

In the following discussion, an LTE module is used as an example of along range wireless communication module, and any type of wirelesscommunication module or wireless communication system other than the LTEmodule, which can generate interference to the reception Rx of the LTEmodule, is expressed using one term “Industrial, Scientific and Medical(ISM)”, although the present invention is not limited thereto. That is,the following discussion is based on assumption that an LTE system is afirst wireless communication system and another wireless communicationsystem, such as BT, Wi-Fi, or GPS system, which may cause in-devicecoexistence interference to a UE supporting the first wirelesscommunication system, is a second wireless communication system, forexample, an ISM system.

Now, specific examples of in-UE coexistence interference will bedescribed. In band #40 (2300˜2400 MHz), LTE TDD downlink reception maybe performed. In this band, the ISM system may generate in-UEcoexistence interference to the downlink reception of the LTE system. Ofcourse, on the contrary, in band #40 (2300˜2400 MHz), LTE TDD uplinktransmission may be performed, which may generate in-UE coexistenceinterference to the reception of the IDM modules.

In order to avoid such in-UE coexistence interference, various schemeshave been discussed, which generally include a Frequency DivisionMultiplexing (FDM) scheme, a Time Division Multiplexing (TDM) scheme,and a Power Control (PC) scheme.

The FDM scheme is a scheme of avoiding interference by spacing frequencybands of an LTE signal and an ISM signal apart from each other, and mayspecifically include a scheme of spacing the frequency band of an LTEsignal apart from a fixed ISM band and a scheme of spacing the ISM bandaway from the frequency band of the LTE signal.

Meanwhile, the PC scheme is a scheme of lowering the LTE transmissionpower or ISM transmission power to a predetermined level, so as toimprove the reception quality of the counterpart signal, therebyavoiding the interference.

The TDM scheme is a scheme of divisionally using the temporal area (timeaxis) for the transmission/reception of an LTE signal and thetransmission/reception of an ISM signal, so as to prevent overlappingbetween them in the temporal area (time axis). Specifically, a DRX basedTDM scheme, an HARQ protection TDM scheme, and an autonomous denial TDMscheme are being discussed as the TDM scheme. Those three types ofspecific TDM schemes are described below in more detail.

The TDM scheme can be applied to a case of using one CC band also.However, since the TDM scheme is a technology divisionally using timeresources, the interference may become too large or may even make thecommunication nearly impossible according to the type of traffic used inthe UE.

Further, although the FDM scheme cannot be used in a situation usingonly one CC band, it is advantageous in that it can perfectly avoid theband in which the interference occurs. Therefore, unlike the TDM, theFDM can prevent the interference from increasing according to the typeof the traffic.

Meanwhile, in a general communication system, when a UE moves from anSeNB, which is a serving eNB or source eNB to which the UE is currentlyconnected, to a TeNB, which is a new or target eNB, it is necessary toperform a handover procedure. The handover procedure releases theconnection to the SeNB and establishes the connection with the TeNB, soas to enable a continuous communication.

Now, the handover procedure will be briefly described. First, when asituation requiring a handover occurs, the SeNB transmits an RRCconnection reconfiguration message (RRCConnectionReconfiguration) to theUE. Upon receiving the RRC connection reconfiguration message, the UEreestablishes an RRC connection with a corresponding TeNB and thentransmits an RRC connection reconfiguration completion message(RRCConnectionReconfigurationComplete) to the TeNB.

Meanwhile, RLF may occur due to various causes between the eNB and theUE, which include an out of synchronization, a failure in the RRCconnection setup, a failure in the RRC connection reconfiguration, afailure in the RRC connection reestablishment, and an arrival at themaximum retransmission number of times in the Radio Link Control (RLC).

Among the causes, the failure in the RRC connection reconfiguration hasa concept including a failure in the handover, and the RRC connectionreconfiguration message includes mobility control information(mobilityControlInfo) when the handover fails.

Further, during the RRC connection reestablishment, the UE firsttransmits an RRC connection reestablishment request message(RRCConnectionReestablishmentRequest) to the eNB, and this message mayinclude a cause value as information on the cause of the RLF. The causevalue may include reconfiguration failure (ReconfigurationFailure),handover failure (HandoverFailure), and other failure (OtherFailure)according to types of the cause.

TABLE 1 Example of RRC connection reestablishment request message --ASN1START RRCConnectionReestablishmentRequest ::= SEQUENCE {criticalExtensions CHOICE { rrcConnectionReestablishmentRequestRRCConnectionReestablishmentRequest-IEs, criticalExtensionsFutureSEQUENCE { } } } RRCConnectionReestablishmentRequest-IEs ::= SEQUENCE {ue-Identity ReestabUE-Identity, reestablishmentCauseReestablishmentCause, spare BIT STRING (SIZE (2)) } ReestabUE-Identity::= SEQUENCE { c-RNTI C-RNTI, physCellId PhysCellId, shortMAC-IShortMAC-I } ReestablishmentCause ::= ENUMERATED {reconfigurationFailure, handoverFailure, otherFailure, spare1 } --ASN1STOP

Now, the meaning of each cause value will be described. The handoverfailure (HandoverFailure), which is a cause value corresponding to thefailure in the handover, implies an RLF occurring during the handover.That is, this cause value corresponds to a case in which an RLF occurssince the timer T304, started after the eNB transmits an RRC connectionreconfiguration message to the UE at the time of handover, has expired.In more detail, this cause value corresponds to a case in which the RRCconnection reconfiguration procedure by the RRC connectionreconfiguration message including the mobility control information(mobilityControlInfo) has failed.

Next, the reconfiguration failure (ReconfigurationFailure), which is acause value implying the reconfiguration failure, indicates areconfiguration failure having occurred during the typical RRCconnection reconfiguration process except for the handover, and theother failure (OtherFailure) corresponds to a case in which an RLF hasoccurred due to other problems except for the above two causes. Forexample, the other failure (OtherFailure) may correspond to a case inwhich an RLF has occurred due to out of synchronization or a case inwhich an RLF indicated by the RLC has occurred.

In the case in which such an RLF occurs, if the Access Stratum (AS)security has not been activated, the RRC connection is released and acorresponding cause value is set as the other failure (OtherFailure). Ifthe AS security has been activated, the RRC connection reestablishmentis performed.

Meanwhile, due to the in-UE coexistence interference as described above,an RLF may occur and handover may thus fail. FIG. 1 illustrates examplesof RLF which may occur due to in-UE coexistence interference.

A of FIG. 1 corresponds to a case in which in-UE coexistenceinterference occurs only within a target cell. If in-UE coexistenceinterference as shown in A of FIG. 1 occurs during a handover procedure,the handover fails.

B of FIG. 1 corresponds to a case in which in-UE coexistenceinterference occurs within both a source cell and a target cell duringan intra-frequency handover procedure. In this case also, the handoverfails.

C of FIG. 1 corresponds to a case in which in-UE coexistenceinterference has already occurred only within a source cell before thehandover event occurs. In this case, it is possible to consider that RLFhas occurred in the source cell and the handover has failed. D of FIG. 1corresponds to a case in which in-UE coexistence interference hasalready occurred within both a source cell and a target cell before thehandover event occurs. This case also corresponds to handover failure.

In order to prevent handover failure due to the in-UE coexistenceinterference, it is necessary to apply various technologies of avoidingin-UE coexistence interference as described above during the handoverprocedure.

Particularly, in order to prevent handover failure due to in-UEcoexistence interference, the present disclosure proposes a scheme inwhich an SeNB provides TDM information (including TDM patterninformation and TDM activation information) to a UE and the UE performsa handover procedure and a data transmission/reception procedure with aTeNB according to the provided TDM information.

FIG. 2 is a signal flow diagram of a handover method for avoiding in-UEcoexistence interference according to an embodiment of the presentinvention.

The handover method for avoiding in-UE coexistence interferenceaccording to the present embodiment may include the steps of: when thereis a possibility that in-UE coexistence interference may occur,including TDM information for avoiding in-UE coexistence interference inmobility control information (mobilityControlInfo) within a RRCconnection reconfiguration message (RRCConnectionReconfiguration) andthen transmitting the RRC connection reconfiguration message(RRCConnectionReconfiguration) to a UE by an SeNB (step S220);performing a random access (for example, by transmitting a random accesspreamble) to a TeNB by the UE (step S230); transmitting an access grantmessage according to the TDM information to the UE by the TeNB (stepS240); and transmitting an RRC connection reconfiguration message to theTeNB by the UE (step S250). Of course, after step S250, TDM data istransmitted or received between the UE and the TeNB according to the TDMinformation (step S260). As a result, it is possible to minimize thesignal interference of an ISM module.

If necessary, the handover method may further include, before step S220,the steps of: when the SeNB transmits a handover request message to theTeNB, transmitting the TDM information to be included in the mobilitycontrol information, together with the handover request message, to theTeNB by the SeNB (step S205); and transmitting a handover admission OKmessage to the SeNB after identifying the TDM information by the TeNB(step S210).

Steps 205 and 210 as described above are necessary in order topreviously notify the TeNB of a particular UE to be handovered to theTeNB, a requirement to perform TDM transmission/reception in order toavoid in-UE coexistence interference, and TDM information (including TDMpattern) indicating details of the TDM transmission/reception. Ofcourse, if the TeNB previously knows the particular UE, the requirementto perform TDM transmission/reception, and the TDM information, stepsS205 and S210 may be omitted.

In step S220, the TDM information for avoiding in-UE coexistenceinterference may be either specific TDM pattern information or TDMactivation information indicating only On/Off of the TDM scheme. The TDMinformation for avoiding in-UE coexistence interference will bedescribed later in more detail.

Further, although not shown, instead of transmitting the TDM informationfor avoiding in-UE coexistence interference when the SeNB transmits anRRC connection reconfiguration message to the UE, the TDM informationfor avoiding in-UE coexistence interference may be transmitted to the UEor TeNB through separate signaling.

Specifically, the step (step S230) of performing a random access to aTeNB by the UE may be, but is not limited to, a step of establishing acontention-free Random Access Channel (contention-free RACH). Further,the random access procedure in step S230 may include either only a stepof transmitting a preamble or the entire random access procedure.

The establishing of the contention-free RACH refers to an operation ofcomparing a Cell Radio Network Temporary Identifier (C-RNTI) of the UEreceived from the SeNB in step S205 with the preamble allocated in stepS210. In other words, in step S230, the TeNB identifies whether thepreamble transmitted from the UE is identical to the preamble selectedby the TeNB in step S210.

When the preamble transmitted from the UE is identical to the preambleselected by the TeNB, the TeNB recognizes the TDM pattern for the UEthrough the identified preamble and transmits an access grant messageaccording to the TDM pattern to the UE in step S240. Then, the UEtransmits an RRC connection reconfiguration complete message accordingto the TDM information in step S250, and performs a communication withthe TeNB to transmit or receive data to or from the TeNB in step S260.

In this process, the operation based on the TDM pattern may not besequentially performed from step S240. In other words, the UE maytransmit data according to the TDM pattern after receiving an accessgrant message from the TeNB and then transmitting the RRC connectionreconfiguration complete message. Therefore, in the present invention,the sequence between steps S240, S250, and S260 of the TDM-basedoperation may be changed and those steps may be performed at differenttime points according to the operations of the system and the UE.

Hereinafter, TDM pattern information as an example of the TDMinformation, TDM activation information, and mobility controlinformation including the TDM pattern information and the TDM activationinformation will be described.

As described above, specific TDM schemes in the in-UE coexistenceinterference technology include a DRX based TDM scheme, an HARQprotection TDM scheme, and an autonomous denial TDM scheme.

The TDM information of the present embodiment refers to information on aspecific applied TDM scheme among the various TDM schemes. Moreparticularly, the TDM information may be either TDM pattern informationor flag type TDM activation information indicating only On/Off of theTDM transmission/reception of the LTE.

Hereinafter, a specific configuration of the TDM pattern informationapplied to the present embodiment will be described. However, the TDMpattern information is not limited to the TDM pattern informationdescribed below and should be understood as having a concept includinginformation on all types of TDM schemes used in order to avoid the in-UEcoexistence interference.

A handover method for avoiding in-UE coexistence interference accordingto another embodiment of the present invention may include the followingsteps.

In step S205, the SeNB transmits a handover request message including aC-RNTI of the UE to the TeNB. In this event, the SeNB may include TDMpattern information of the UE in the transmitted message.

In step S210, the TeNB identifies the C-RNTI of the UE and transmits ahandover admission OK message to the SeNB. In this event, since the useof the TDM pattern is not employed, the TeNB transmits a handoveradmission OK message including contents denying the use of the TDMpattern on the UE to the SeNB. Therefore, in step S220, the SeNBtransmits an RRC connection reconfiguration message including TDM OFFinformation to the UE.

Then, in step S225, the UE identifies the execution of the handover.Also, the UE identifies that it is impossible to apply the TDM pattern.

Thereafter, in step S230, the UE transmits an RACH request messageincluding an allocated preamble to the TeNB and the TeNB determineswhether a preamble in the RACH request message transmitted from the UEis identical to the preamble having been allocated by the TeNB itself.In step S240, the TeNB transmits an access grant message to the UEthrough the identified preamble.

When the UE having received the access grant message determines that itis necessary to apply the TDM in order to avoid the in-UE coexistenceinterference, that is, in order to apply the TDM pattern, the UEtransmits an RRC connection reconfiguration complete message includingTDM pattern information or TDM request information for avoiding in-UEcoexistence interference to the TeNB in step S250.

Therefore, the TeNB may identify the TDM pattern information or TDMrequest information included in the RRC connection reconfigurationcomplete message, so as to allow a TDM operation.

In other words, when the TeNB identifies that it is necessary to performTDM of the UE after the handover of the UE even though the TeNB hasidentified that it is impossible to apply the TDM to the UE during thehandover with the SeNB, the TeNB may identify the TDM patterninformation or approval on the TDM request, so as to allow the TDMoperation.

Thereafter, in step S260, the TeNB may apply the TDM pattern andtransmit or receive data to or from the UE.

FIG. 3 illustrates a DRX-based TDM scheme, which is one of schemes foravoiding in-UE coexistence interference applicable to the presentembodiment.

The DRX-based TDM scheme, which is one of schemes for avoiding in-UEcoexistence interference, is a scheme in which a predetermined patternperiodicity is divided into a scheduled period and an unscheduled periodand LTE transmission is prevented in the unscheduled period in order toavoid interference between the LTE and the ISM. However, main LTEtransmission, such as random access transmission or HARQ retransmission,may be allowed even in the unscheduled period.

According to an embodiment to which handover of the DRX-based TDM schemeis applied, transmission in a preamble transmitting period and a RandomAccess Response (RAR) receiving period may be allowed even when thepreamble transmitting period and the RAR receiving period belong to theunscheduled period. Especially, in the RAR receiving period,transmission of the ISM may be autonomously denied. The concept ofautonomous denial will be described later as an embodiment applyinganother TDM scheme. Further, transmission of an RRC connectionreconfiguration complete message for completing the handover after thePAR receiving may be especially allowed even in the unscheduled periodin order to enable the message to be transmitted before the timer T304,which is a handover failure timer, expires.

In the scheduled period, transmission of the ISM is prevented whiletransmission of LTE is allowed, in order to avoid interference betweenthe LTE and the ISM. Of course, similarly to the unscheduled period, animportant ISM transmission, such as a beacon (in the case of Wi-Fi), maybe allowed even in a corresponding scheduled period. In other words, inorder to protect the important ISM transmission, the LTE transmissionmay be prevented even in the scheduled period.

In the case where the DRX-based TDM scheme as described above is used,the TDM pattern information of the present embodiment may includeinformation on the pattern cycle, the length of the scheduled period,and the length of the unscheduled period, etc. Further, the TDM patterninformation may include special signaling for protecting an importantISM transmission, such as a beacon, that is, may include ISMtransmission protection information in the scheduled period. An exampleof the ISM transmission protection information in the scheduled periodmay include a cycle of beacon signaling and subframe offset information.The subframe offset may be determined based on that SFN=0 and radioframe number=0.

FIG. 4 illustrates an HARQ protection TDM scheme, which is one ofschemes for avoiding in-UE coexistence interference applicable to thepresent embodiment.

In the HARQ protection TDM scheme, when data is transmitted based onHARQ, a retransmitted signal is first protected, that is, an HARQretransmission is inevitably performed.

For example, if TDM transmission is performed in order to avoid in-UEcoexistence interference and retransmission is not performed, theperformance of the system will be remarkably degraded. In order to solvethis problem, the HARQ protection TDM scheme determines the TDMtransmission pattern in consideration of the retransmission cycle.

In FIG. 4, it is assumed that, among 10 subframes within the mth radioframe, the first and sixth subframes (SFN=1 and 6) have been reservedfor the downlink transmission of LTE and the second and seventhsubframes (SFN=2 and 7) have been reserved for the uplink transmissionof LTE (scheduled subframes).

Therefore, in the case of downlink HARQ retransmission, initialtransmission of a Physical Downlink Shared Channel (PDSCH) is performedat the first subframe (SFN=1) and retransmission of the PDSCH isperformed at the first subframe (SFN=1) of the (m+1)th radio frame (ofcourse, FIG. 4 shows the configuration in which ACK/NACK information istransmitted through an uplink subframe having an SFN of 7, too).

In the HARQ protection TDM scheme as described above, subframes,scheduling of which is prevented in order to avoid in-UE coexistenceinterference, are not to be used for transmission of an LTE signal inorder to protect an ISM band.

Similarly to the DRX-based TDM scheme, the HARQ protection TDM schemealso may prevent LTE transmission even at a subframe reserved for thetransmission, in order to enable important ISM signal transmission. Onthe contrary, the LTE transmission may be allowed even in a subframe forcoexistence, scheduling of which is prevented, when transmission ofimportant LTE messages, such as a random access signal or a systeminformation paging signal, is necessary.

In such TDM schemes, the TDM pattern information of the presentembodiment may be configured by pattern information in the form ofbitmap indicating subframe(s) for LTE. The number of subframes indicatedby one bit may be either one or more than one. That is, a value obtainedby multiplying the total length of the bitmap by the number of subframesindicates a cycle of the TDM pattern and the value (0 or 1) of each bitmay indicate a scheduled subframe or an unscheduled subframe.

For example, if TDM pattern information having a TDM pattern cycle of 20subframes is given as a bitmap of 1001001000 and if it is assumed that 0indicates an unscheduled subframe (i.e. subframe, transmission of whichis prevented), each bit in the TDM pattern information implies twoconsecutive subframes and subframes having SFNs of 0, 1, 6, 7, 12, and13 (SFN=0, 1, 6, 7, 12, 13) in the TDM pattern cycle correspond toscheduled subframes, which are subframes for the uplink or downlinktransmission of LTE.

Of course, each bit on the TDM pattern information may imply more thantwo consecutive subframes. For example, one bit may include informationon 4, 5, or 10 consecutive subframes. In this event, TDM patterninformation having a TDM pattern cycle of 20 subframes may be bitmapinformation of 5, 4, or 2 bits.

FIG. 5 illustrates an autonomous denial TDM scheme, which is one ofschemes for avoiding in-UE coexistence interference applicable to thepresent embodiment.

The autonomous denial TDM scheme is a scheme in which a UE deniestransmission of a predetermined signal in order to protect ISM receptionin the case of LTE or in order to protect LTE reception in the case ofISM.

FIG. 5 corresponds to an example of denying a predetermined LTE signalin order to protect the reception of an ISM signal, wherein even when aneNB has allocated an uplink transmission to a UE, the UE denies theallocation and does not perform the uplink transmission in order toprotect the reception of an ISM signal.

In FIG. 5, the upper subframe structure corresponds to reception andtransmission of an LTE signal and the lower structure corresponds toreception and transmission of an ISM signal.

In more detail, at the eighth subframe of LTE, reception is denied sincethe reception may be subjected to interference by the transmission of anISM signal. Meanwhile, at the 14th subframe of LTE, transmission isdenied in order not to have an influence on the reception of an ISMsignal. Likewise, in the ISM also, a case where there is a difficulty inthe reception due to interference of LTE or a case where the ISMtransmission or reception is denied in order to protect the LTEreception are marked by “X” in the subframes of the lower structure ofFIG. 5.

Meanwhile, the TDM pattern information according to an embodiment of thepresent invention as shown in FIGS. 3 to 5 may be included in themobility control information (mobilityControlInfo) transmitted from theSeNB to the UE in step S220. Otherwise, the TDM pattern information maybe included in the RRC connection reconfiguration complete messageincluding the TDM pattern information transmitted from the UE to theTeNB in step S250.

Tables 2 and 3 below are an example of mobility control informationincluding TDM information according to an embodiment of the presentinvention, wherein Table 2 corresponds to an example of mobility controlinformation including TDM pattern information and Table 3 corresponds toan example of mobility control information including TDM activationinformation.

TABLE 2 Mobility control information including TDM pattern information-- ASN1START MobilityControlInfo ::= SEQUENCE { targetPhysCellIdPhysCellId, carrierFreq CarrierFreqEUTRA OPTIONAL, -- Cond HO-toEUTRAcarrierBandwidth CarrierBandwidthEUTRA OPTIONAL, -- Cond HO-toEUTRAadditionalSpectrumEmission AdditionalSpectrumEmission OPTIONAL, -- CondHO-toEUTRA t304 ENUMERATED { ms50, ms100, ms150, ms200, ms500, ms1000,ms2000, spare1}, newUE-Identity C-RNTI, radioResourceConfigCommonRadioResourceConfigCommon, rach-ConfigDedicated RACH-ConfigDedicatedOPTIONAL, tdmIcoPattern TDMICOPattern OPTIONAL, -- Need OP ... }

In the example of mobility control information of Table 2, the value“tdmIcoPattern” corresponds to the TDM pattern information of thepresent embodiment, and the TDM pattern information may be determinedaccording to the schemes shown in FIGS. 3 to 5. The UE transmits andreceives LTE data to and from the TeNB according to the received TDMpattern. As a result, it is possible to prevent handover failure due toin-UE coexistence interference.

TABLE 3 Mobility control information including TDM activationinformation -- ASN1START MobilityControlInfo ::= SEQUENCE {targetPhysCellId PhysCellId, carrierFreq CarrierFreqEUTRA OPTIONAL, --Cond HO-toEUTRA carrierBandwidth CarrierBandwidthEUTRA OPTIONAL, -- CondHO-toEUTRA additionalSpectrumEmission AdditionalSpectrumEmissionOPTIONAL, -- Cond HO-toEUTRA t304 ENUMERATED { ms50, ms100, ms150,ms200, ms500, ms1000, ms2000, spare1}, newUE-Identity C-RNTI,radioResourceConfigCommon RadioResourceConfigCommon,rach-ConfigDedicated RACH-ConfigDedicated OPTIONAL, tdmIco ENUMERATED{TRUE, FALSE) OPTIONAL, -- Need OP ... }

In the example of mobility control information of Table 3, the value“ENUMERATED{TRUE, FALSE}” of the item “tdmIco” corresponds to the TDMactivation information of the present embodiment, and the TDM activationinformation functions as an On/Off type indicator indicating whether toperform a TDM operation at the time of handover in order to avoid in-UEcoexistence interference. For example, the value “TRUE” may be used tocommand the execution of a special TDM operation during the handoverprocedure.

In the case of using the TDM activation information indicating onlyon/off of the TDM in order to avoid the in-UE coexistence interference,the UE may implement various types of TDM schemes as described above.For example, when there is an existing TDM scheme, it is possible toapply the existing TDM scheme between the UE and the TeNB. That is, itis possible to use the existing TDM scheme in the handover procedurewithout change.

As another example, when there is a TDM pattern transferred to the TeNBin the handover procedure through separate signaling and the UErecognizes the transferred TDM pattern, even only a TDM activationindication based on the TDM activation can enable TDM transmission orreception by a corresponding TDM pattern.

As another example, when there is a TDM pattern determined in advance asa default, even only a TDM activation indication based on the TDMactivation can enable TDM transmission or reception by a correspondingTDM pattern.

By using the handover procedure as described above, when there is in-UEcoexistence interference, transmission and reception of an LTE signalare performed according to a predetermined TDM pattern between a UE anda TeNB in order to avoid the in-UE coexistence interference, so as toprevent handover failure due to the in-UE coexistence interference.

FIG. 6 is a flowchart of an operation of a UE during a handoverprocedure according to an embodiment of the present invention.

First, the UE receives an RRC connection reconfiguration message from anSeNB (step S610).

Next, the UE determines whether the RRC connection reconfigurationmessage includes TDM information for avoiding in-UE coexistenceinterference (step S620).

The TDM information for avoiding in-UE coexistence interference may beTDM pattern information as shown FIGS. 3 to 5 or TDM activationinformation indicating On/Off of the TDM operation. The TDM informationmay be included in, but is not limited to, the mobility controlinformation within the RRC connection reconfiguration message.

When the TDM information is included in the RRC connectionreconfiguration message, the UE identifies the TDM information torecognize that it should perform a TDM operation with the TeNB at thetime of handover, and then performs a random access to the TeNB (stepS630). For example, the UE may perform a contention-free RACH.

After performing the random access to the TeNB, the UE performs datatransmission and reception with the TeNB according to a correspondingTDM pattern.

As described above, the random access procedure may include either theentire contention-free RACH access procedure or only the process oftransferring a random access preamble for the RACH.

When the RACH procedure includes only the process of transferring arandom access preamble, the UE may perform the procedure after thetransmission of the random access preamble among the RACH procedureaccording to the TDM pattern directly after transmitting the randomaccess preamble.

After receiving access grant information according to a correspondingTDM pattern from the TeNB (step S640), the UE transmits an RRCconnection reconfiguration complete message(RRCConnectionReconfigurationComplete) to the TeNB (step S650).

After the handover is completed as described above, the UE performs datatransmission and reception with the TeNB according to a correspondingTDM pattern (step S660).

Of course, when TDM information is not included in the RRC connectionreconfiguration message, the UE performs a typical handover operation(step S670).

The typical handover operation in step S670 refers to a handoverprocedure, such as receiving of an access grant or a random access witha typical TeNB, which does not reflect the TDM. Further, even after thehandover, the UE performs data transmission and reception with the TeNBaccording to a typical process without performing the TDM transmissionand reception in consideration of the in-UE coexistence interference.

Meanwhile, according to another embodiment of the present invention, thehandover of step S670 may be performed as follows.

The UE receives the RRC connection reconfiguration message from the SeNBand identifies the execution of the handover. This state corresponds toa case in which the handover of the UE has been normally performedbetween the SeNB and the TeNB and the SeNB transmits an RRC connectionreconfiguration message, which does not include a TDM pattern, or an RRCconnection reconfiguration message, which includes TDM activationinformation indicating TDM OFF, to the UE. Therefore, the UE identifiesthat it is impossible to apply the TDM pattern. Thereafter, the UEtransmits an RACH request message including an allocated preamble to theTeNB and then receives an access grant message from the TeNB.

Upon receiving the access grant message, the UE identifies that it isnecessary to apply the TDM in order to avoid in-UE coexistenceinterference within the UE itself, and may transmit an RRC connectionreconfiguration complete message including TDM pattern informationand/or TDM request information indicating the application of the TDMpattern to the TeNB. Then, the TeNB identifies the TDM patterninformation or TDM request information included in the RRC connectionreconfiguration complete message and then grants or allows the TDMoperation. Therefore, the UE can apply the TDM pattern to transmit orreceive data to or from the TeNB.

FIG. 7 is a flowchart of an operation of the SeNB during a handoverprocedure according to an embodiment of the present invention.

The SeNB determines whether there is a possibility that the handover mayfail due to the in-UE coexistence interference (step S710). When it isnecessary to avoid the in-UE coexistence interference, the SeNBgenerates an RRC connection reconfiguration message including TDMinformation (including TDM pattern information or TDM activationinformation) according to the embodiments described above and transmitsthe generated RRC connection reconfiguration message to the UE (stepS720).

Of course, when there is no possibility that the handover may fail orwhen the in-UE coexistence interference is not taken into consideration,the SeNB generates a typical RRC connection reconfiguration message(which does not include TDM information) and transmits the generated RRCconnection reconfiguration message to the UE (step S730).

Further, if necessary, before performing step S720, the SeNB maytransmit a handover request message, including the same TDM informationas the TDM information to be transmitted to the UE, to the TeNB (stepS712), and may receive a handover admission OK message, as a response tothe transmitted handover request message, from the TeNB (step S714).

The TDM information (TDM pattern information or TDM activationinformation) transmitted from the SeNB to the UE may be included in, butis not limited to, the mobility control information within the RRCconnection reconfiguration message.

FIG. 8 is a flowchart of an operation of a TeNB during a handoverprocedure according to an embodiment of the present invention.

The TeNB receives a contention-free random access preamble transmittedthrough a random access by a UE during a handover procedure (step S810).

Then, the TeNB identifies the received random access preamble, so as todetermine whether the UE is a UE requiring TDM transmission (step S820).The determination of whether the UE is a UE requiring TDM transmissioncan be performed by identifying the TDM pattern information and theC-RNTI of the UE received from the SeNB before the handover anddetermining whether the received random access preamble is a randomaccess preamble relating to the C-RNTI of the UE allocated by the TeNBitself. That is, the TeNB identifies or determines whether the randomaccess preamble of the UE is a random access preamble previouslyallocated by itself.

When it is necessary to perform a TDM operation in order to avoid in-UEcoexistence interference between the TeNB and the UE to be handovered,the TeNB performs a Random Access Response (RAR) by transmitting anaccess grant message according to predetermined TDM information (stepS830).

Next, the TeNB receives an RRC connection reconfiguration completemessage from the UE (step S840), and then performs TDM-based datatransmission or reception with the UE (step S850).

Further, according to another embodiment of the present invention, theTeNB may receive an RRC connection reconfiguration complete messageincluding TDM request information or TDM pattern information from the UEin step S840.

In other words, the UE recognizes that it is necessary to apply the TDMin order to avoid in-UE coexistence interference of itself, andtransmits an RRC connection reconfiguration complete message includingTDM request information requesting application of the TDM or TDM patterninformation required for the application of the TDM to the TeNB, and theTeNB identifies the TDM request information or the TDM patterninformation included in the RRC connection reconfiguration completemessage and grants the TDM operation.

Of course, as a result of the determination in step S820, when it is notnecessary to perform a TDM operation in order to avoid in-UE coexistenceinterference between the UE and itself, the TeNB performs a typicalhandover procedure (step S860).

The typical handover procedure includes operations of receiving a RandomAccess Response (RAR), which is not based on the TDM, receiving an RRCconnection reconfiguration complete message, and transmitting andreceiving data to and from the UE in a state which is not applied to theTDM.

Further, although not shown, the operation of the TeNB shown in FIG. 8may further include a step in which the TeNB receives and stores TDMinformation (including TDM pattern information or TDM activationinformation) on a particular UE when receiving the handover requestmessage from the SeNB or the UE or through another signaling.

FIG. 9 is a block diagram of a UE according to an embodiment of thepresent invention.

The UE 900 according to the present embodiment includes an RRCconnection reconfiguration message receiver 910 for receiving an RRCconnection reconfiguration message from the SeNB for handover, a TDMdeterminer 920 for determining whether the RRC connectionreconfiguration message includes TDM information for avoiding in-UEcoexistence interference, such as TDM pattern information or TDMactivation information, a Random Access (RA) execution unit 930 forperforming a random access with the TeNB, and a transceiver 940 fortransmitting an RRC connection reconfiguration complete message to theTeNB and performing TDM-based data transmission and reception with theTeNB.

The TDM determiner 920 determines whether mobility control informationof the RRC connection reconfiguration message received from the SeNB forthe handover includes TDM information for avoiding in-UE coexistenceinterference, wherein the TDM information may be either specific TDMpattern information as shown in Table 2 and Table 3 or TDM activationinformation for indicating On/Off of the TDM operation. Of course, theTDM information may include both the TDM pattern information and the TDMactivation information.

The RA execution unit 930 transmits a contention-free random accesspreamble to a corresponding TeNB.

When there is TDM pattern information included in the TDM information,the transceiver 940 receives an access grant message from the TeNBaccording to the corresponding TDM pattern. Further, the transceiver 940generates an RRC connection reconfiguration complete message andtransmits the generated RRC connection reconfiguration complete messageto the TeNB, and then transmits or receives data to or from the TeNBaccording to the corresponding TDM pattern. As a result, the UE canperform an LTE signal transmission or reception while avoiding in-UEcoexistence interference.

Further, when there is no TDM pattern information, the transceiver 940performs a typical procedure for handover and data transmission orreception.

FIG. 10 is block diagram of an SeNB according to an embodiment of thepresent invention.

The SeNB 1000 according to the present embodiment is an apparatus forperforming a handover capable of avoiding in-UE coexistenceinterference, and includes a TDM determiner 1010 for determining whethera TDM operation is necessary for the handover so as to avoid in-UEcoexistence interference, an RRC connection reconfiguration messagegenerator 1020 for, when it is determined that a TDM operation isnecessary, generating an RRC connection reconfiguration messageincluding TDM information, such as TDM pattern information or TDMactivation information, and a message transmitter 1030 for transmittingthe generated RRC connection reconfiguration message to the UE.

Also, the SeNB 1000 may further include a handover request messageprocessor 1040 for generating a handover request message including TDMinformation and transmitting the generated handover request message tothe TeNB.

Moreover, the SeNB 1000 may further include a TDM information determiner1050 for determining information on a specific TDM pattern to be usedduring a handover between a particular UE and the TeNB.

The RRC connection reconfiguration message generator 1020 generates anRRC connection reconfiguration message which contains TDM patterninformation or TDM activation information as shown Table 2 or Table 3within a mobility control information element of the message.

FIG. 11 is block diagram of a TeNB according to an embodiment of thepresent invention.

The TeNB 1100 according to the present embodiment is a target-sideapparatus for performing a handover capable of avoiding in-UEcoexistence interference, and includes an RA processor 1110 forreceiving a contention-free random access preamble from a UE to behandovered, a TDM determiner 1120 for determining whether to perform aTDM operation between the TeNB and a corresponding UE, an access grantprocessor 1130 for generating an access grant message according topredetermined TDM information and transmitting the generated accessgrant message to the UE, and a transceiver 1140 for receiving an RRCconnection reconfiguration complete message from the UE according to apredetermined TDM pattern and transmitting or receiving data accordingto the predetermined TDM pattern.

Further, if necessary, the TeNB may further include a TDM informationreceiver 1150 for receiving TDM information to be applied during thehandover from the SeNB or the UE.

The TDM information receiver 1150 may receive the TDM information fromthe SeNB or the UE either when it receives a handover request messagefrom the SeNB or through a separate signaling rather than receiving ofthe handover request message.

When the TeNB knows the TDM pattern to be applied during the handover ofa particular UE or receives TDM pattern information from the SeNB or theUE, the TeNB performs the handover procedure and data transmissionthereafter according to the TDM pattern.

According to the embodiments as described above, the SeNB transmitsparticular TDM information to the UE (and to the TeNB, too, ifnecessary), and the UE performs a handover operation with the TeNBaccording to a corresponding TDM pattern, so as to prevent handoverfailure due to the in-UE coexistence interference.

While the exemplary embodiments have been shown and described, it willbe understood by those skilled in the art that various changes in formand details may be made thereto without departing from the spirit andscope of this disclosure as defined by the appended claims and theirequivalents. Thus, as long as modifications fall within the scope of theappended claims and their equivalents, they should not be misconstruedas a departure from the scope of the invention itself.

1-16. (canceled)
 17. A method of performing a handover in a wirelesscommunication system, the method comprising: transmitting a handoverrequest message of a User Equipment (UE), which supports a firstwireless communication system and a second wireless communicationsystem, to a Target Source evolved Node-B (TeNB), by a Source evolvedNode-B (SeNB); receiving a handover admission OK message from the TeNB,by the SeNB; and generating a Radio Resource Control (RRC) connectionreconfiguration message for a handover and transmitting the RRCconnection reconfiguration message for the handover to the UE, in orderto enable the UE to perform the handover to the TeNB, by the SeNB,wherein the handover request message includes Time Division Multiplexing(TDM) information related to avoidance of In-Device Coexistence (IDC)interference of the UE.
 18. The method as claimed in claim 17, whereinthe TDM information related to the avoidance of the IDC interference ofthe UE comprises Discontinuous Reception (DRX)-based TDM patterninformation, and the DRX-based TDM pattern information comprises one ormore of information on a pattern cycle, information on a length of ascheduled period, and information on a length of a unscheduled period.19. The method as claimed in claim 18, wherein transmission of a signalby the first wireless communication system is prevented in theunscheduled period.
 20. The method as claimed in claim 17, wherein theTDM information related to the avoidance of the IDC interference of theUE comprises TDM pattern information, and the TDM pattern informationcomprises information on a subframe pattern considering a HybridAutomatic Repeat Request (HARQ) retransmission cycle in the firstwireless communication system.
 21. The method as claimed in claim 20,wherein the information on the subframe pattern considering the HARQretransmission cycle comprises one or more of: information on a subframein which HARQ-based transmission and reception in the first wirelesscommunication system are performed; and information on a subframe inwhich transmission of a signal by the first wireless communicationsystem is prevented.
 22. The method as claimed in claim 21, wherein theTDM pattern information is information on a subframe pattern in a bitmapform.
 23. The method as claimed in claim 17, wherein the first wirelesscommunication system is a Long Term Evolution (LTE) system, and thesecond wireless communication system is a communication system otherthan the LTE system.
 24. The method as claimed in claim 23, wherein thesecond wireless communication system is an Industrial Scientific andMedical (ISM) system.
 25. A handover apparatus of a Source evolvedNode-B (SeNB), which performs an operation related to a handover of aUser Equipment (UE) supporting a first wireless communication system anda second wireless communication system, the handover apparatuscomprising: a handover request message processor to transmit a handoverrequest message to a Target Source evolved Node-B (TeNB), and to receivea handover admission OK message from the TeNB; a Radio Resource Control(RRC) connection reconfiguration message generator to generate an RRCconnection reconfiguration message for a handover; and a messagetransmitter to transmit the generated RRC connection reconfigurationmessage to the UE in order to enable the UE to perform the handover tothe TeNB, wherein the handover request message includes Time DivisionMultiplexing (TDM) information related to avoidance of In-DeviceCoexistence (IDC) interference of the UE.
 26. The handover apparatus asclaimed in claim 25, wherein the TDM information related to theavoidance of the IDC interference of the UE comprises DiscontinuousReception (DRX)-based TDM pattern information, and the DRX-based TDMpattern information comprises one or more of information on a patterncycle, information on a length of a scheduled period, and information ona length of a unscheduled period.
 27. The handover apparatus as claimedin claim 26, wherein transmission of a signal by the first wirelesscommunication system is prevented in the unscheduled period.
 28. Thehandover apparatus as claimed in claim 25, wherein the TDM informationrelated to the avoidance of the IDC interference of the UE comprises TDMpattern information, and the TDM pattern information comprisesinformation on a subframe pattern considering a Hybrid Automatic RepeatRequest (HARQ) retransmission cycle in the first wireless communicationsystem.
 29. The handover apparatus as claimed in claim 28, wherein theinformation on the subframe pattern considering the HARQ retransmissioncycle comprises one or more of: information on a subframe in whichHARQ-based transmission and reception in the first wirelesscommunication system are performed; and information on a subframe inwhich transmission of a signal by the first wireless communicationsystem is prevented.
 30. The handover apparatus as claimed in claim 29,wherein the TDM pattern information is information on a subframe patternin a bitmap form.
 31. The handover apparatus as claimed in claim 25,wherein the first wireless communication system is a Long Term Evolution(LTE) system, and the second wireless communication system is acommunication system other than the LTE system.